The statements in this section merely provide background information related to the present disclosure and cannot constitute prior art.
Commercial meat-bird poultry production in the U.S. includes broilers (chickens), turkeys and ducks. Commercial poultry farms raise thousands, and often many tens of thousands, of poultry birds inside large poultry barns. For example, a chicken being raised for human consumption spends its entire life indoors in a climate controlled atmosphere designed to efficiently grow the birds to full, marketable size. Temperature control is a major factor in maintaining the climate controlled atmosphere for maximum efficiency. As such, fuel costs for heating are one of the major expenses in commercial poultry operations, typically the largest cost to poultry farmers aside from feed costs. Poultry barns are located in rural areas where there is often no source of cheap fuel available. Propane, which is significantly more expensive than natural gas, is often the only option. Due to the unpredictable price of heating fueling, propane-a poultry farmer's ability to make a profit on a flock raised during the winter months is sometimes jeopardized by high fuel costs. Unexpected increases in fuel costs sometimes determines whether a given flock produces a profit or a loss for the farmer.
Health is another consideration affected by the climate controlled atmosphere of a poultry barn-both the health of the birds and the health of the human consumer who eventually purchases a bird for consumption. In addition, the climate controlled atmosphere of the poultry barn has a great effect on the weight gain efficiency of the flock as the birds grow from hatchlings into marketable sized broilers.
More particularly, the climate of a poultry barn can be defined as the sum of environmental factors which influence the health and behavior of the flock. Climatic factors include temperature, humidity, air cleanliness, degree of light, and other such factors. The climate of a poultry barn has a great influence on the health of the birds as well as the efficiency of growing them to market size. Chickens raised in unfavorable climatic conditions are at risk to develop respiratory and digestive disorders and possibly exhibit behavioral issues. In addition to health and behavioral considerations, poor climatic conditions cause inefficiencies in feed utilization, thus reducing the daily rate of gain of the flock. In short, poultry raised in poor climatic conditions cannot be expected to perform optimally. Additionally, in order to maintain livability and prevent disease, different kinds of antibiotic medicine are widely used in the industry. Today, more and more poultry producers are starting to produce antibiotic free (ABF) poultry for the sake of consumer's health. In order to maintain productivity of poultry with antibiotic medicine reduced, or removed, a high quality environment is highly required.
The interaction between the need for clean air in a poultry barn and the requirement to maintain a given temperature at various stages of poultry production is generally known. It typically takes seven to eight weeks to grow a hatchling broiler from several ounces up to a marketable weight of five to seven pounds. During this time the poultry barn is maintained at different heat levels, depending upon the age of the broilers. Young hatchling broilers require a much warmer environment than older, larger birds. When the flock is first introduced into the poultry barn the temperature is kept at around 85 to 90 degrees Fahrenheit for chickens, and around 90 to 95 degrees for turkeys. The temperatures are gradually reduced until reaching a final temperature of around 60 to 70 degrees Fahrenheit. During the winter months farmers spend a great deal of money on fuel costs to keep the barn heated to the initial temperatures which are as high as 90 degrees.
In order to keep the poultry barn air clean, large fans, including side-wall fans and tunnel fans, are used to circulate the air, while constantly venting a portion of the polluted air out of the barn and replacing it with clean, fresh air from the outside. For example, ventilation is utilized for the removal of polluted air with high concentration of ammonia (NH3), carbon dioxide (CO2), Carbon monoxide (CO) and other harmful gases resulting from poultry litter and fuel burning inside the barn. However, during the winter months in the Midwestern and northern states the clean, fresh air coming into the barn is too cold for optimal climactic conditions. Therefore, it is necessary to constantly heat the barn to compensate for the incoming clean, fresh air being introduced into the barn's climate. With conventional climate control systems energy consumption and the associated costs for poultry farms is second only to feed costs. Various embodiments of the present disclosure capitalize on the heat being expelled with the dirty air, using heat recovery units to capture part of that heat for the incoming fresh air.
Heat recovery systems are used in other fields of industry, including implementations to recover at least some of the waste heat being vented from factories and office buildings. Typically, the conventional heat recovery systems use a metal heat exchanger system since metal interface surfaces tends to conduct heat more efficiently than plastic, vinyl, and other non-metallic synthetic materials. However, there are characteristics specific to the poultry industry that pose a drawback in attempting to use a conventional metal heat recovery systems for expelled poultry barn air. The expelled air from poultry barns is quite dirty, containing a high concentration of dust, feathers and other airborne particles as well as ammonia. Ammonia and other gases in a poultry barn are quite corrosive to conventional metallic heat recovery systems. Moreover, the airborne particles include dust from dried poultry feces, a material that is quite corrosive and often includes viruses, bacterial content and parasites. The pollutants in poultry barn air—in particular, the feces dust, feathers and feather parts-result in an airborne pollutant that is very lightweight, somewhat sticky, and prone to causing diseases in poultry and humans. The poor quality of air, including airborne feces dust, feathers and feather parts, renders conventional metal heat recovery systems unsatisfactory for poultry barns. Conventional heat recovery systems with high efficiency metal interfaces quickly build up a layer of dirt and grime from airborne dust, feces dust, feathers and feather parts, and even fly manure. This is especially true of conventional heat recovery units that use closely spaced fins to more efficiently translate the heat from one air stream to another. The buildup of grime and impurities, in turn, corrodes the surface area of conventional heat recovery systems which lowers the heat exchange efficiency, results in reduced air flow, and in some cases, can even cause air flow blockages.
Meat poultry is raised in flocks consisting of birds of the same age. Hatchlings are introduced into a barn at a young age, generally in sufficient quantities to populate the entire barn. In many operations, the birds remain together for approximately five to eight weeks—the time it takes to reach marketable weight and size. To avoid propagating disease from one flock to the next, farmers thoroughly clean out the poultry barn from top to bottom after a flock is sold out of it. The cleaning typically is done by scrubbing and using high pressure water streams to remove viruses, bacteria, fungi, and parasites. In addition the post-flock cleaning generally involves the use of strong soaps and chemical solvents such as Stalosan F, Net Tex Viratec, Poultry Shield, and other such commercially available poultry barn cleaners known to those of ordinary skill in the art. Commercial poultry barn cleaning agents typically include one or more of the following types of disinfectants in various concentrations: aldehydes (e.g., formalin, formaldehyde, glutaraldehyde); chlorine-releasing agents (e.g., sodium hypochlorite, chlorine dioxide, sodium dichloroisocyanurate, chloramine-T); iodophors (e.g., povidone-iodine, poloxameriodine); phenols and bis-phenols (e.g., triclosan and hexachlorophene); quaternary ammonium compounds and peroxygens (e.g., hydrogen peroxide and peracetic acid).
The thorough post-flock clean is performed to kill any viruses, bacteria, fungi, and parasites present in the poultry barn after the flock is sold. An attempt to use a conventional metallic heat recovery system would prove problematic in view of the rigorous post-flock poultry barn cleaning. Many of the aforementioned chemical solvents and disinfectants used to clean poultry barns are corrosive to metals used in conventional metallic heat recovery systems. Moreover, in addition to corrosion caused by the chemical cleaners and disinfectants, conventional metallic heat recovery systems would tend to corrode over time due to the pollutants that are specific to the meat poultry industry—that is, due to the feces dust, feathers and feather parts from a poultry flock. Once a conventional metallic heat recovery system begins to corrode it becomes nearly impossible to clean it sufficiently for the purposes of a commercial meat poultry barn. The one known commercial alternative would be to use conventional metallic heat recovery systems constructed of stainless steel. This, however, would be cost prohibitive and impractical for a commercial meat poultry operation. Stainless steel is quite expensive and would be difficult to work with in order to tailor fit it to a particular poultry barn.